Hard compositions of matter



Patented July 12, 1938 PATENT oFFice' HARD COMPOSITIONS F MATTER PhilipM. McKenna, Latrobe, Pa.

No Drawing. Original application September 6, 1935, Serial No. 39,505.Divided and this application February 24, 1937, Serial No. 127,559

Claims.

This application is a division of my pending application for LettersPatent, Serial No. 39,505, Hard compositions of matter, filed September6,

1935, upon which U. S. Letters Patent No. 5 2,093,844 issued September21, 1937, and other divisional applications are filed herewith.

My invention relates to new hard compositions of matter. It has to do;more particularly, with certain novelcompositions of matter, notable fortheir combined strength and hardness, so that they are particularlyuseful in the construction of tools, dies and other articles ofwear-resisting or corrosion-resisting nature, as well as articles whichare required to resist deformation .or de- 1 struction at hightemperatures and pressures. In particular, my invention' relates to theproduction of new hard compositions of matter, which are particularlyusefulas the hard bits or tips including the cutting edges of toolsintended for cutting hard materials. These compositions are alsoparticularly adapted to use as wire-drawing dies.

The principal object of my invention is to provide new hard-compositionsof matter, which have greater combined strength, hardness and resistanceto deformation at high temperatures and pressures than any hardcompositions of matter heretofore known.

A further object of my invention is to provide new hard'compositions of.matter, having great combined strength, hardness and resistance todeformation. which are made from macro-crystalline carbides of themetals of the group including tantalum and columbium, which carbides arecharacterized, notonly by their macrocrystalline form, but by a carboncontent in true monatomic ratio to the metal present. In other words, itis an object of my invention to produce new hard compositions of matter,having useful characteristics as indicated, which are made from the newmacro-crystalline product, instead of the amorphous material heretoforeknown, for .example, as tantalum carbide and consisting of carburizedtantalum; in which the carbon is not .present in exact monatomic ratioto the tantalum.

It is a further object of my invention to provide novel hardcompositions of -matter, including tantalum carbide or columbiumcarbide, together with tungsten metal or molybdenum metal, or. both, anda metal or metals of the iron group, 'in which the proportion of themetals of the group including tungsten and molybdenum to the totalnon-carbide ingredients .of the composition is substantially higher thanhas been possible heretofore without sacrificing strengt h. This is animportant feature, because an increased proportion of tungsten ormolybdenum, or both, imparts to the hard compositions of matterv theproperty of resisting deformation, especially at high temperatures, but,heretofore, it has not been possible to include as much tungsten ormolybdenum as was desired, because of the deleterious efiect of theamorphous tantalum carbide or amorphous columbium carbide upon thestrength of the resulting composition.

Further objects! and objects relating to details and economies ofproduction and operation, will definitely appear from the detaileddescription to follow. In one instance, I accomplish the ob- ,iects ofmy invention by the devices and means set forth in the followingspecification. 'My invention is clearly defined andpointed out in theappended claims.

Hard compositions of matter have beemknown, heretofore, which consistedof an amorphous material, called tantalum carbide, together with certainproportions of 'a metal or metals of the group including tungsten andmolybdenum, and a metal or metals of thegroup including iron, coibaltand nickel. The best of these hard compositions of matter was composedas follows:

Amorphous tantalum carbide, 78 per cent, nickel,

10.2 per cent, tungsten, 11.8 per cent; This material was madebycomminuting the amorphous tantalum carbide and metallic tungsten in aball mill, using nickel balls, in a bath of naphtha, until the mixturecontained the tantalum carbide, tungsten and nickel in the desireddegree of fineness and in the required proportions above given. Thenaphtha was then removed entirely by heating in a partial vacuum at ared heat. ,A piece was then formed from this dried powder of the desiredshape and that piece heated in an electric furnace, under a-partialvacuum, corresponding approximately to a pressure of from 70 to 80microns of mercury, for forty minutes. As the result of this treatment,a hard composition of matter was formed having a Rockwell-A hardness of86.5. The strength of the piece thus formed is indicated by the factthat the piece, having a thickness of .200 inch and a width-of .375inch, resting on supports 11/16 of an inch apart, when pressed in themiddle with a ,one centimeter Brinell ball, broke under a loadof 1980kilograms.

Another example of similar hard compositions of matter, heretoforeknown, is one which comprised 80 per cent amorphous tantalum carbide, 8per cent nickel and 12 per cent tungsten. This composition had aRockwell A" hardness of 87.75 and broke, under the same conditions asspecified above, at a load of 1500 kilograms. These two hardcompositions of matter, just described, represent what I believe to bethe most desirable hard compositions of this type heretoproportions of ametal or metals of the group including tungsten and molybdenum, and of ametal or metals of the iron group. 'The' powdered mixture thus formedafter drying 011 some pf the naphtha is pressed to the shape of thepiece .to'

- be made, the linear dimensions, however, being phous in character, inthat it did not present crystalline form to the unaided human eye. Forthe purposes of this sp cification I define macrocrystalline as ha gparticles which average greater than .01 millimeter in largest crosssection dimension and amorphous" as having particles which average lessthan .01 millimeter in largest cross section dimension. I understandthat there is another sense, in which all solid bodies may be describedas crystalline, and may be shown to have ordered atomic arrangement by Xray methods, or to have crystalline form which may be seen under themicroscope, but I do not use the term in this sense, in thisspecification.

' It will be observed that, in the 'two compositions above-mentioned,the nickel and tungsten together constitute 22 per cent and 20 per ceht,respectively, of the composition, and that the tungsten constitutes 53.6percent and 60 per cent, respectively, of the ingredients of thecomposition other than the tantalum carbide. I ad believed it desirable,if possible, to increase t e proportion of tungsten in the non-carbidein; gredients of the composition, but I had found that this was notfeasible, heretofore, because a further increase in the proportion oftungsten resulted in a decrease in the strength of the composition,which was undesirable, as the piece would break or chip when used as ametal cutting tool. Thus, although a higher percentage of tungsten isdesirable, in order to give the composition increased resistan'ce todeformation,

' especially at high temperatures, this increased proportion of tungstencould not be obtained,

heretofore, without an accompanying decrease in the strength of thecomposition.

l-Iard compositions of matter have been proposed, her'etofore, includingcolumbium carbide, of the amorphous type in which thecarbon .is notpresent in..true monatomic ratio to the columbium, together with certainproportions of tungstenand cobalt, but such hard compositions 'werlacking in practical value, because of the weakness of the material.

It has also been proposed, heretofore, to make was only about one-thirdo hard compositions of matter from a mixture of amorphous tantalumcarbide and amorphous columbium carbide the particles of which wereunited into a cohesive mass by a mixture of metallic iron andmolybdenum. Although such compositions were hard, they were lacking instrength as they would brea under aload which the breaking loadof theamorphous tantalum carbide composition. heretofore-referred-to.

In general, my invention co compositions. of matter'made froma macro-crystalline carbide or the metals of the group memo"- ins tantalum andcolumbium, containing carbon '-in true monatomic ratio to the metal ormetals I present. The macro-crystalline carbide forming .the startingingredient for the new composition is comminuted, in a non-oxidizing.both. as by a" ball mill, for such length of time as needed to ness andto incorporate inthe mixture the which takes place in. the process, andthe piece thus shaped is heated, under a partial vacuum, in an electricfurnace, for about forty minutes,- at a temperature of about 1430 C. Theheating should require about two hours in all, one hour and twentyminutes being consumed in gradually raising the furnace to the ultimatetemperature and removing the gas and vapors, and the furnace beingmaintained at the ultimate temperature for about forty minutes. As aresult of this treatment, the shaped piece shrinks into a cohesive bitof like shape, but smaller dimensions, and it is believed that the metalor metals of the group including tungsten and molybdenum, and the metalor metals of the iron group, included in the composition, function tounite the grains of carbide into a cohesive mass. As will be shownhereinafter, the resulting composition has a hardness equal to that ofthe compositions heretofore referred to', with a strength and resistanceto deformation, especially at high temperatures, which exceeds that ofsaid compositions.

The macro-crystalline carbides which I contemplate using in my presentinvention, and the method of making such carbides are fully described inmy pending application for United" States Letters Patent, Serial No.31,521, filed July 15, 1935, entitled, "Carbides of tantalum and likemetals and method of producing the same",

- to which cross-reference is hereby made.

The invention of the present, application contemplates novel hardcompositions of matter embodying a macro-crystalline simple carbide,that is, either tantalum carbide or columbiumcarbide.

My application, Serial. No. 39,505, o. s.

" 2,093,844, of which this application is a division,

ent is tantalum carbide or columbium carbide and the minor constituentis formed by a carbide or carbides of ametal or metals of the groupconsisting of tantalum, columbium, titanium and zirconium. The other ofsuch divisional applications is directed to compositions or matter .em--

" was hers;

reduce the crystals to the desired degree of flnebodying multi-carbidesof metals of the group consmting of tantalum, columbium, titanium andzirconium in. which the maior constituent iscolumbium carbide. r .Thefollowing specific examples of new compositions of matter, made inaccordance with myinvention from macro-crystalline carbides of the "chSerial No. 31,521.'Itis necessary, in' forming hard compositions ofmatter in these. to provide other metals, whic ,I believe-perio form acohesive mass and forming a matrix-in ter described in mypending' Iapplication fornited States \Letters Patent. .70

T a the function of uniting the grains of carbide .andNi, from to 15 percent.

I have found that a. very satisfactory hard composition of matter may beformed from macro-crystalline'TaC, W and Ni, as follows:

The TaC may constitute from 55 to 82 per cent of the composition, W,from to 40 per cent, The range of proportions which I prefer is TaC,from 70 to 82 per cent, W, from 11 to 38 per cent, and Ni, from 5 to 12per cent. The following are the specific proportions of the ingredientsin two specimens of this composition, that I have made and found useful:

TaC W Ni Percent Percent Percent Spec. A 74. 6 18.0 7. 4 Spec. B? 7811.2 10.8

In eabh of. these specimens, the tantalum carbide used as the startingmaterial was macro crystalline and had a carbon content in truemonatomic ratio to the tantalum present and, in that respect,distinguishes from the amorphous material ,heretofore known as tantalumcarbide. The specimens, above mentioned,.'were subjected to tests todetermine their hardness, strength and resistance to deformation,especially at high temperatures. Specimen A had a Rockwell A hardness of89.8 and a breaking strength of 1720kiIograms, determined in the sameway as with the prior compositions'hereinbefore mentioned. Lathe testsshowed that this composition of matter suffered lessdeformation, at thehigh temperatures resulting from the cutting action, than the priorcompositions. In other words, this new hard compositionof matter,specimen A, did not show a tendency to mushroom under conditions whichwould cause the prior compositions to do so. Tests upon specimen B,which, in proportion of ingredients, was about the same as one of theprior compositions referred to, differing' therefrom in that it is madefrom macro-crystalline tantalum carbide instead of amorphous material,showed that it had a Rockwell A hardness of 87.62 and a' breaking pointof 2320 kilograms.

Comparison with theprior compositions shows that specimen A was harderthan the prior compositioncontaining '78 per cent amorphous tantalumcarbide and not quite so strong, having a breaking strength of 1720kilograms, as compared with 1980 kilograms. This specimen did, however,exhibit increased resistance to deformation at the cutting temperature.Specimen A was about as hard as the prior composition containing 80 percent amorphous tantalum carbide and' stronger, having a breaking pointof 1720 kilograms, as compared with 1500 kilograms. Specimen B, whichcontained 78 per cent macrocrystalline tantalum carbide, was harder thanthe corresponding prior composition and about as hard as the priorcomposition containing 80 per cent. amorphous tantalum carbide. It washaving a breaking strength of 2320 kilograms as compared with 1980kilograms and 1500 kilostronger than either of these prior compositions,

grams, respectively. It appears, therefore, that these new compositionsof matter, made from macro-crystalline TaC, show a better combination ofstrength, hardness and resistance to,

deformation than the prior compositions.

} The following is a specific example of a new composition of matter,made in accordance with my present invention, using macro-crystallineCbC as the starting material. The macro-crystalline CbC may constitutefrom 40 to 75 per cent of the composition, W may constitute from 16 to33 per cent," and Ni, from 10 to 30 per cent.

If M0 is substituted for W, it may constitute from 9 to 20 per cent ofthe composition and, in that case, Ni' may constitute from 12 to 33 percent.

I prefer that, where W is used in the composition, the CbC should rangefrom 55 to 65 per cent of the composition, W, from 18 to 22 per cent,and Ni, from to 25 per cent. If, however, Mo be used in place of W, thepreferred range of proportions is as follows: CbC, 65 to 72 per cent,Mo, 10 to 14 per cent, and Ni, 18 to 27 per cent. The specificproportions of ingredients used in the making of a specimen of thiscomposition from macro-crystalline CbC is as follows: CbC, 59.4 percent, W, 20.7 per cent, and

"Ni, 19.9 per cent. Tests on this specimen showed that it had a RockwellA hardness of 85.2 and a breaking strength of 2030 kilograms. While notquite so hard as prior compositions made of amorphous tantalum carbide,it exceeded these compositions in strength and was far superior instrength and resistance'to deformation to any materials heretofore madefrom amorphous columbium carbide.

The following are the specific proportions of a composition made frommacro-crystalline CbC, using molybdenum in place of tungsten: CbC, 73per cent, Mo, 12 per cent, and Ni, 15 per cent. I believe .that thiscomposition also exhibits an excellent combination of strength, hardnessand resistance to deformation, especially at high temperatures.

The specific examples of hard compositions of matter, made in'accordancewith my invention, Just'given, are illustrative of the new compositionsthat may be made by the use, as starting materials, of themacro-crystalline carbides of, the character described and claimed in mypending application for United States Letters Patent, Serial No..31,521. course, that I have not described specifically all ofthepossible combinations. In general, molybdenum may be substituted for allor a part of the tungsten in any of these compositions, it beingunderstood that, in making such substitution, the proportion of themetalused should be adjusted It will be understood, of

in the ratio of the atomic'weights of tungsten or a major proportion ofthe nickel undesirabla' To express the range of proportions of thesecompositions, I prefer to state the proportions in molecular and atomicpercentages of the ingredients. I 'prefer that the carbide shallcontained by a Gaede mercury diffusion pump which draws oil and absorbsgases and vapors, including stitute from 68.1 to 55.64 molecular percent of the composition, that a metal or metals of the group includingtungsten and molybdenum should constitute from 15.58 to 17.66 atomic per5 cent of the composition, and that a metal or metals of the iron groupshall constitute from 20.5 to 26.7 atomic per cent of the composition.

' I believe that, where the carbide is columbium carbide, compositionshaving a better combined tion may be produced by substitutingmolybdenum, in whole or in part, for the tungsten.

. The preferred methods for making these new compositionsof matter aredescribed in detail ground and comminuted in a ball mill with metallictungsten or molybdenum, and,with nickel,

cobalt or iron, the comminution with the metallic ingredientsbeingeontinued until the ingredients reach the desired state of finenessand until they are present'in the proper proportions. The comminution ispreferably carried out in a bath of naphtha, or other suitable material,to prevent oxidation, and it is preferable that the naphtha bepreviously purified, as by subjecting it to freshlycut surfaces ofsodium, to remove oxygen and sulphur-containing compounds.

The finely comminuted particles are partially dried, 1 to 5 per cent ofthe-naphtha being left to protect the powder from o d ation, and thethoroughly mixed particles are hen pressed into bits of the desiredshape and of a size such as to compensate for the shrinkage of 15 to 25per cent which will later take place in the heat treatment.

5 The bits are then subiectecLto heat treatmentunder a vacuum of from to'l'microns of mercury pressure, in an electric furnace, for about fortyminutes at a temperature of from 1400 C. to 1500 0., depending upon theratio. of the metals, the temperature being slowly raised until itreaches this temperature. The vacuum is ohthe vapors coming from thehydrocarbon, and the 55 outlet of the mercury diffusion pump isconnected to an oil pump. The bits are preferably heated .in anelectricinduction furnace, being placed within a covered graphitecrucible. I

Whenever I use the term macro-crystalline" in w the appended claims,withreference to a carbide or multi-carbide, I mean a carbide ormulti-carbide having particles which averagegreater than .01 millimeterin largest cross sectiondimension and produced by the reaction between ametal or 65 metals and carbon in the presence of a menstruum other thanthe reactants.

. I am awe re that the products herein disclosed 'may be variedconsiderably, without departing r from the spirit of my invention, and,therefore, I

claim my invention broadly as indicated by the appended claims. I

whatIclaimis: p '1. The new hard composition of matter,consubstantially'of a matrix formed of an strength, hardness andresistance to deformamatter, upon which U. S. Let- 1 September ill.

.-'-In general, the macro-crystalline carbide is f" nickel.

of the group consisting of tuna with a metal of the iron alloy of ametal sten and molybdenum group and particles of a comminuted macrocrystalline carbide of a metal of the group con-. sisting of tantalumand columbium embedded in said matrix, saidmacro-crystalline carbidebeing characterized by a carbon content in monatomic ratio to the metalor metals present. I

2. The new-hard composition of matter consisting of particles ofcomminuted macroecrystalline carbide of a metal of the group consistingof tantalum and columbium, characterized by a carbon content inmonatomic ratio to the metal present united by a matrix formed from analloy of a metal of the, group consisting of tungsten and molybdenumwith a metal of the iron group.

3. The new hard composition of matter consisting of from 55.64 to 68.1molecular per cent of a: comminutedmacro-crystalline carbide of a metalof the group consisting of tantalum and columbium, in which the carboncontent is in monatomic ratio to the metal present, from 15.58 to 17.66atomic per cent of a metal of the group consisting of tungsten andmolybdenum, and from 20.5 to 26.7 atomic per cent of a metal of the irongroup.

4. A new hard composition of matter consisting substantially ofparticles of a comminuted macro-crystalline tantalum carbide, in whichthe carbon content is in monatomic ratioto the tantalum, embedded in amatrix constituted by an alloy of a metal of the group consisting oftuna stem and molybdenum with a metal of the iron 5. A new hardcomposition of matter consisting substantially of from 70 to 82 per centof a comminuted macro-crystalline tantalum carbide, in which the carboncontent is in monatomic ratio to the tantalum, from 11 to 38 per centtungsten, and from 5 to 12 per cent nickel.

6. A new vhard composition of matter consisting substantially of 74.6per cent of a comminuted macro-crystalline tantalum carbide, in whichthe carbon content is in monatomic ratio to the tantalum, 18' per centtungsten and 7.4 per cent nickel.

7. The new hard composition of matter consisting substantially of '18per cent of a comminuted.

macro-crystalline tantalum carbide, in which the carbon content is inmonatomic ratio to the tanta1um, 11.2 per cent tungsten, and 10. 8 percent nickel.

8. The new hard composition of matter consistingsubstantially ofparticles of comminuted macro-crystalline columbium carbide, in whichthe carbon content isin monatomic ratio to the,

columbium, embedded in a matrix constituted by an alloy of a metal ofthe group consisting of tungsten and "molybdenum with a metal of theiron group.

9. A new hard compositionof matter consists ing substantially of from to65 per cent [ofa comminuted macro-crystalline colum hide, .in which thecarbon content is in monatomic Y ratio to the columbium, from 18 to 22per cent tungsten.-and from 15 to 25 per cent nickel.

10. Anew hard composition of matter consisting sub'stantiallyof per centof a comminuted macro-crystalline columbium carbide, in which the carboncontent is in monatomic ratio to the columbium, 20 per cent tungsten and20 percent

